Preparations before planting garden trees and 3 principles to follow

The principle of garden tree planting is to follow the laws of tree growth and development, provide corresponding planting conditions and care measures, promote root regeneration and recovery of physiological metabolic functions, coordinate the contradiction between aboveground and underground growth and development, show vigorous roots, strong trees, luxuriant branches and leaves, and abundant flowers and fruit, and fully achieve the ecological indicators and landscape effects required by garden greening design. So what preparations are needed before planting garden trees? Which principles should be followed?

1. What preparations are needed before planting garden trees?

1. Clarify the design intent

Understanding the planting task Garden tree planting is part of garden greening engineering, and only with a deep understanding of the engineering design intent can the design requirements be met. For example, for the same ginkgo, when planted as a street tree, male plants should be selected, and the trees should be required to be uniform in size, usually planted at equal spacing and symmetrically; when used as a landscape tree, either female or male plants may be selected, and the tree size specifications may differ. When planted, a single tree may be appreciated alone, or three to five trees may be planted together, but attention must be paid to the space for crown development. Furthermore, diseases and insect pests caused by improper mixed planting of tree species should be avoided. For example, mixing Chinese scholartree and paulownia can cause outbreaks of stink bugs; Chinese juniper should be kept away from Rosaceae tree species such as crabapple and apple to avoid apple-juniper rust.

2. On-site terrain treatment

Fixed-point surveying and line setting According to the design drawings, carrying out terrain treatment at the planting site is an important measure to improve the survival rate of planting. The planting site should be reasonably connected with surrounding roads, facilities, etc., with good drainage and waterlogging reduction, and construction waste and debris around it should be cleared. Fixed-point surveying and line setting according to construction drawings is the basis for the designed landscape effect. For fixed-point line setting of street trees, the road edge or road central axis is generally used as the basis, and both sides are required to be neat. For tree planting without precise fixed planting points on the design drawings, especially for tree groups, the planting range can be marked out first, and the specific positions can be comprehensively considered according to the design idea, tree size, and current site conditions. Generally, the principle is that the development between plants does not interfere with each other.

3. Digging planting pits

Preparing tree pits The size and depth of tree pits should be determined according to tree specifications and soil layer thickness, slope size, groundwater level, and soil moisture. Practice has proved that large pits are beneficial to the growth and development of tree roots. For example, for a tree with a diameter at breast height of 5-6 cm and relatively good soil quality, a pit with a diameter of 80 cm and a depth of 60 cm can be dug. Generally, tree pits should be no smaller than 1 cubic meter, and shrub pits should be no smaller than 0.5 cubic meter. In areas with strong wind and sand, large pits are not conducive to moisture conservation, so small pits are suitable for planting.

2. 3 principles of garden tree planting

Principle 1: Suitable tree for suitable site

First, it is necessary to understand the ecological habits of the tree species and their adaptability to the ecological environment of the planting area, and there must be successful introduction trials and mature cultivation and care techniques. In particular, the selection and application of new flowering shrub varieties should be more cautious than garden tree species valued for foliage or form, because the adaptability of such tree species is shown not only in tree survival but also in the perfect expression of ornamental flower and fruit traits. The simplest way to apply the principle of suitable tree for suitable site is to select native tree species with excellent traits as backbone tree species. Especially in the planning and design of ecological forests, the principle of giving priority to native tree species should be implemented in order to create an ecological community effect.

Second, local special microclimate conditions at the planting site can be used to break through the limitations of the original ecological environment, meet the growth and development requirements of newly introduced tree species, and achieve suitable tree for suitable site. For example: building hills and directing water, setting up peripheral barriers; improving soil and applying fertilizer to change soil properties; bundling grass for cold protection to enhance tree cold resistance. In addition, buildings can be used to block wind and protect against cold, and small courtyards can enclose and gather warmth, so as to reduce the damage of low winter temperatures and expand the range for moving southern trees northward.

Third, the control of groundwater level plays an important role in the principle of suitable tree for suitable site. Too high a groundwater level is a major factor affecting the survival of tree planting. Among existing garden tree species, moisture-tolerant tree species are extremely scarce. In particular, deodar cedar, southern magnolia, peach, and cherry blossom are extremely sensitive to water accumulation around the roots. During planting, measures such as raising the ground surface or deep ditch drainage can be used to facilitate tree survival and normal growth and development. Another important part of suitable tree for suitable site is mastering the light adaptability of tree species. Garden tree planting is different from general afforestation. It mostly uses a community ecological planting model combining trees, shrubs, and groundcover plants to express landscape effects. Therefore, when multiple tree species are planted in groups, consideration of the planting positions of shade-tolerant tree species and sun-loving flowering shrubs becomes extremely prominent.

Principle 2: Timely planting The planting period of garden trees

It should be determined according to tree characteristics and the climatic conditions of the planting area. Generally, deciduous tree species are mostly planted after leaf fall in autumn or before bud break in spring. During this period, the tree is dormant, injured roots recover easily, and the survival rate of planting is high. For evergreen tree species, in the warm winter areas of the south, autumn planting is mostly used; in areas with severe winter cold, autumn drought often causes branch dieback and prevents successful overwintering, so spring planting before new shoots sprout is preferable; in areas with severe spring drought, rainy season planting may be carried out.

1. Spring planting In spring, the tree ends dormancy and begins growth and development, and this is the main tree planting season in most areas of China. In addition, spring planting conforms to the phenological sequence in which trees first grow roots and then develop branches and leaves, which is conducive to the balance of water metabolism. Especially in areas with severe winter cold or for tree species that are not very cold-resistant, spring planting can save the labor of winter protection. In areas with autumn drought and strong winds, evergreen tree species are also suitable for spring planting, but the time may be slightly delayed. Tree species with fleshy roots, such as dogwood, magnolia, and tulip tree, are also better planted in spring because their roots are prone to low-temperature freezing injury. Spring work is busy and labor is tight, so according to tree species' bud-break habits and the soil thawing periods of different regions, winter slack time should be used to make plans. Among tree species' bud-break habits, larch and silver willow are the earliest, poplar, willow, peach, and plum are next, and elm, Chinese scholartree, oak, and jujube are the latest. The soil thawing period is related to climatic factors, site conditions, and soil texture. Deciduous tree species should be planted early in spring, and planting can begin as soon as the soil thaws. In North China, spring planting is mostly from early March to late April, while in East China, mid-February to late March is best.

2. Autumn planting Autumn planting

The tree's water demand decreases, and both air temperature and soil temperature are relatively high. The underground part of the tree has not yet fully healed, and the roots cut during planting can heal as early as possible and new roots can grow. For autumn planting in North China, large-specification seedlings are often used to enhance the tree's overwintering ability. For autumn planting in East China, it can be extended to early November to late December. In the severe cold areas of Northeast China and northern Northwest China, autumn planting should be carried out after leaf fall and before the land freezes.

3. Rainy season (summer) planting

Affected by the dry and wet monsoon of the Indian Ocean, the Southwest region has distinct dry and rainy seasons, and planting in the rainy season is preferable. If the rainy season occurs in high-temperature months, short-term high temperatures and strong light can easily cause water metabolism imbalance in newly planted trees, so it is necessary to grasp the local rainfall patterns and the rainfall situation of that year, and plant during continuous rainy periods. In the Jiangnan region, there is also experience in using the climatic characteristics of the “plum rain” period for summer planting.

Principle 3: Suitable method for suitable planting The planting methods of garden trees

Bare-root planting or balled-and-burlapped planting should be adopted according to the growth characteristics of the tree species, the growth and development state of the tree, the planting period of the tree, and the environmental conditions of the planting site.

1. Bare-root planting

This method is mostly used for small evergreen seedlings and deciduous tree species. The key to bare-root planting is to keep the root system intact. The main roots should not be too long, and lateral roots and fibrous roots should be retained as much as possible. From digging the seedlings to planting, the roots must be kept moist. Root dipping is one of the commonly used protection methods and can increase the transplant survival rate by 20%. The slurry ratio is: superphosphate 1 kg + fine loess 7.5 kg + water 40 kg, stirred into a paste. To improve the survival rate of planting, wet grass can be used for covering during transport to prevent the roots from drying out in the wind.

2. Balled-and-burlapped transplanting

Evergreen tree species and some tree species that are difficult to survive with bare-root planting, such as Chinese chestnut, pecan, horse chestnut, and magnolia, are mostly planted with soil balls. Large tree planting and growing-season planting also require soil balls to improve the survival rate.